1835.] On Dysluite. 285 



Article V. 



On Dysluite. By Thomas Thomson, M.D., F. R.S., &c. 

 Regius Professor of Chemistry ?n the University of 

 Glasgow. 



The mineral of which I mean to give an account in this 

 paper, was sent me at least seven years ago, by Dr. Torrey 

 of New York; and some years after, I received a fresh 

 supply from Mr. Nutall. Dr. Torrey informed me in his 

 letter, that it had been discovered by two American Minera- 

 logists, (I think they were Mr Keating and Mr. Vanuxem ; 

 though of this I am not quite sure, as I have not Dr. Tor- 

 rey's letter at hand,) who gave it the name of dysluite, from 

 its difficult fusibility with carbonate of soda, and who were 

 engaged in analyzing it. This information prevented me 

 from doing any thing more than giving it a cursory ex- 

 amination, which satisfied me that dysluite was a new 

 mineral of rather a curious nature, and highly deserving 

 the attention of mineralogists. Being unwilling to deprive 

 the American mineralogists of the credit which might 

 accrue to them from the analysis, I cautiously abstained 

 from alluding to it, in a paper on the analysis of American 

 Minerals, published in the Annals of the Lyceum of Natural 

 History of New York, in the year 1828. But six years 

 having elapsed since that period, and no analysis nor notice 

 of dysluite having appeared in the interval, I take it for 

 granted, that the American gentlemen have relinquished 

 their intention of prosecuting the analysis, and that, there- 

 fore, I ought no longer to withhold the knowledge of this 

 curious mineral from mineralogists. 



Dysluite occurs at Stirling, in New Jersey, interspersed 

 through a dark coloured limestone, and immediately mixed 

 with crystals of octahedral iron ore and several other 

 minerals, which it is unnecessary to describe here. I ob- 

 tained it by dissolving the limestone in muriatic acid, and 

 picking out the crystals of dysluite from the other crystals 

 and grains with which it was mixed. 



Colour yellowish brown, sometimes lighter, sometimes 

 darker. In grains varying from the size of a mustard seed, 

 to that of a pea ; most of them crystallized in regular octa- 

 hedrons. Texture foliated. Lustre of the faces of cleavage 



